Calculator

_{App icon by andrewjaguirre via macOSicons}

A cross-platform calculator project supporting CLI and Flutter-based UI. 🤖

This project demonstrates a layered architecture for calculating expressions with features like command-line interaction, Flutter UI, and localization.

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Table of Contents

• Overview
• Features
• Screenshots
• Getting Started
• Running Tests
• Windows Platform Support
• Project Structure
• CLI Usage
• Localization
• License

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Overview

This project implements a calculator with two main interfaces:

1. CLI Application: A command-line interface for evaluating mathematical expressions.
2. Flutter Application: A mobile and desktop Flutter UI with interactive buttons.

The application is built with clean architecture principles:

• Data Layer: Manages data sources (local, remote).
• Domain Layer: Contains core business logic (entities, use cases).
• Presentation Layer: Includes CLI and Flutter UI components.

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Features

• CLI Support: Calculate expressions via command-line interaction.
• Interactive UI: Flutter-based calculator app with a responsive layout.
• Localization: Supports English and Korean.
• Scalable Architecture: Clean separation of concerns across layers.
• Cross-Platform: Works on iOS, Android, Windows, macOS, Web, and Linux.

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Getting Started 🚀

Prerequisites

• Dart & Flutter SDK installed (Installation Guide).
• For CLI, ensure Dart is added to your system path.

Running the Flutter Application

The project contains 3 flavors: development, staging, and production.

Use the following commands to run the desired flavor:

# Development
$ flutter run --flavor development --target lib/main.dart

# Staging
$ flutter run --flavor staging --target lib/main.dart

# Production
$ flutter run --flavor production --target lib/main.dart

*Calculator works on iOS, Android, Web, and Windows.

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Screenshots 📸

Below are screenshots demonstrating the application:

Initial Screen	Successful Calculation	Error Handling

• Initial Screen: The home screen where users can input mathematical expressions.
• Successful Calculation: An example of a correct calculation being performed.
• Error Handling: How the app displays errors for invalid input or unsupported operations.

Running Tests 🧪

To run all unit and widget tests, use the following command:

flutter test --coverage --test-randomize-ordering-seed random

To view the generated coverage report, use lcov:

# Generate Coverage Report
$ genhtml coverage/lcov.info -o coverage/

# Open Coverage Report
$ open coverage/index.html

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Windows Platform Support

This section explains how to manage dependencies and build the Windows app, especially when your main development machine is macOS.

1) Dependency Management Principles

• The single source of truth for app/plugin dependencies is pubspec.yaml.
• Use flutter pub get (or flutter pub upgrade) to resolve and update dependencies.
• On Windows, plugin wiring for CMake is generated automatically by Flutter:
  • windows/flutter/generated_plugins.cmake
  • windows/flutter/generated_plugin_registrant.cc
• Do not edit generated files under windows/flutter/generated_* or windows/flutter/ephemeral/*.

What to edit (and what not to edit)

• windows/flutter/CMakeLists.txt: Flutter-managed; avoid manual edits.
• windows/CMakeLists.txt: Top-level Windows build settings; edit only when you need custom native build behavior.
• windows/runner/CMakeLists.txt: Runner target settings; edit only when adding custom C++ source files, compile flags, or manual native linking.

In most Flutter-only feature work, you do not need to edit any of these CMake files.

2) Build Constraints on macOS

• You cannot build a Windows desktop binary directly on macOS.
• Windows builds require a Windows toolchain (Visual Studio C++ and Windows SDK), so build on:
  • a physical Windows machine
  • a Windows VM
  • a CI runner (for example, GitHub Actions windows-latest)

3) Local Windows Build (on a Windows machine)

Prerequisites:

• Install Flutter SDK
• Install Visual Studio 2022 with Desktop development with C++
• Enable Windows desktop support:

flutter config --enable-windows-desktop

Build and run:

flutter pub get
flutter run -d windows
flutter build windows --release

Release output path:

build/windows/x64/runner/Release/

4) CI/CD Setup Example (GitHub Actions)

If you develop on macOS, add a Windows build job so pull requests and pushes validate Windows continuously.

windows-build:
  runs-on: windows-latest
  steps:
    - uses: actions/checkout@v4
    - uses: subosito/flutter-action@v2
      with:
        channel: stable
    - run: flutter pub get
    - run: flutter build windows --release
    - uses: actions/upload-artifact@v4
      with:
        name: windows-release
        path: build/windows/x64/runner/Release/

Tip: keep your existing Linux analysis/test jobs and add this Windows job in parallel for platform coverage.

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Project Structure

The project follows a modular structure:

lib/
├── app/                         # MaterialApp root
├── core/                        # Shared utilities
├── data/                        # Data layer (datasources, repository impl)
├── domain/                      # Domain layer (repository interface)
├── presentation/                # Presentation layer (bloc, UI, CLI)
├── gen/                         # flutter_gen output — do not edit
└── main.dart                    # App entry point

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CLI Usage

Launching the CLI

Run the command:

dart run calculator:interpreter

Available Commands

Command	Description
help	Shows usage instructions.
history	Displays previous calculations.
clear	Clears the console (CLI only).
exit	Exits the application.

Example Interaction

$ dart run calculator:interpreter
Building package executable...
Built calculator:interpreter.
======================================
       CLI Calculator (v1.0)
======================================
Type "help" for usage instructions or "exit" to quit.
> 1/5
Result: 0.2
> 1/4
Result: 0.25
> 1/3
Result: 0.3333333333333333
> 1/2
Result: 0.5
> 1/1
Result: 1.0
> 1/0
Result: Infinity
> history
Calculation History:
- 1/5 = 0.2
- 1/4 = 0.25
- 1/3 = 0.3333333333333333
- 1/2 = 0.5
- 1/1 = 1.0
- 1/0 = Infinity
> help
--------------------------------------
Instructions:
- Enter calculations (e.g., 2+3, 4*5/2).
- Supported operators: +, -, *, /.
- Commands:
  'help'     - Show usage instructions.
  'history'  - Show calculation history.
  'clear'    - Clear the console.
  'exit'     - Exit the application.
--------------------------------------
>

If you want to run a function that returns results immediately, please use the following command.

$ dart run calculator:calculate --help
Building package executable...
Built calculator:calculate.
Usage: dart run calculator:calculate <expression>
Example: dart run calculator:calculate "2+3"

$ dart run calculator:calculate 2+3
Building package executable...
Built calculator:calculate.
Result: 5.0

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Localization 🌐

The calculator draws only glyphs and digits, so it ships no ARB files of its own. lib/app/app.dart registers the three flutter_localizations delegates and declares supportedLocales: [ko, en], which is what makes SDK-provided labels — such as the copy/paste menu on the result display — follow the device locale.

To add app-owned strings later, create lib/l10n/arb/app_ko.arb and app_en.arb, point a l10n.yaml at them, and run flutter gen-l10n.

License

This project is licensed under the MIT License. See the LICENSE file for details.